Band saw apparatus

ABSTRACT

A band saw includes a drive wheel and a fixed, curved band saw guide surface having one or more tracks for one or more band saw continuous strips; lubricant openings in the tracks are accessed from a source of lubricant under pressure to reduce frictional resistance of the band saw moving over the guide surface.

FIELD OF THE INVENTION

The present invention relates to an improvement in band saw apparatusand, particularly, a simplification of the apparatus includingreplacement of the conventional, upper idler wheel with a low frictionguide surface. This arrangement will enhance the control of the tensionin the band saw as well as reduce the expense in constructing andoperating such machinery.

BACKGROUND OF THE INVENTION

In the lumber industry, a number of apparatus has been employed to cuttimber into usable pieces for subsequent operations or usage.Frequently, a wood cant must be cut into fairly thin but elongatedpieces and typically band saws are used to accomplish this operation. Inconventional band saws, such as represented by U.S. Pat. No. 4,061,066,issued Dec. 6, 1977, U.S. Pat. No. 6,745,644 issued Jun. 8, 2004, U.S.Pat. No. 5,1557,989 issued Sep. 24, 1996 and U.S. Pat. No. 5,819,613issued Oct. 13, 1998, an endless band saw is looped around an idlerpulley wheel and a drive wheel which is motor driven which is operatedat high speed to rotate the drive wheel and, hence, the band saw overthe pulley wheel while cants or wooden pieces are transported by aconveyor or manually against the cutting teeth of the band saw. Tensionon the band saw is maintained by adjusting the distance between thecentral axis of rotation of the pulley and the drive wheel. Themaintenance of the proper tension in the band saw loop is critical toefficient cutting operation and the avoidance of damage to the band sawloop. In particular, an improper low tension will result in wastage ofthe wood product since vibration of the loop will increase the size ofthe kerfs or cut made in the wood and can lead to breakage of the banditself.

SUMMARY OF THE INVENTION

In the present invention, the rotatable idler pulley is eliminated andreplaced by a low friction curved surface that has one or more tracksfor individual band saw loops. The drive wheel which is typically butnot always located vertically below the surface provided by the presentinvention may be formed with a corresponding number of tracks to enhanceguidance of the band saw or saws. In addition, the drive wheel may beprovided with sprocket teeth to cooperate with sprocket openings formedalong one edge of the band saw opposite the edge on which the cuttingteeth are formed. Further, the track or each track of the curved surfaceis formed with a number of lubricating openings connected to a source oflubricant under pressure or continuous grooves which will also besupplied with a lubricant under pressure. Air under pressure may also beprovided with the lubricant so that the band saw moving over the curvedsurface will encounter as little frictional resistance as possible.

One advantage of the arrangement of the present invention is thesimplification of a band saw apparatus since the curved guide surfacewill require substantially less maintenance then the idler pulleycurrently in use. Also, typically the idler pulleys presently in use arerelatively heavy as compared with the guide surface used in the presentinvention. The weight saving may significantly extend the life of thedrive motor for the drive pulley. Additionally, the use of a fixed guidesurface will allow the introduction of closely adjacent, multiple looptracks which will be spaced apart at the cutting site by virtue of thedifferent radii of each of the tracks as will become apparent from thefollowing description. Further, the use of the stationary guide surfacewill reduce vibrations in the band saw during use and thereby result ina reduced kerf size and will allow thinner cutting to be accomplished.

The foregoing and other advantages will become apparent as considerationis given to the following detailed description taken in conjunction withthe accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view in side elevation of the apparatus of thepresent invention;

FIG. 2 is a view along lines 2-2 of FIG. 1;

FIG. 3 is a top plan view similar to FIG. 1 of an alternativeembodiment;

FIG. 4 is a side view in elevation of a further alternate embodiment ofthe invention; and

FIG. 5 is a side view is similar to that of FIG. 4 but showingadditional guide tracks;

FIG. 6 is a schematic view of an improved band saw useful with amodified drive wheel;

FIG. 7 is sectional view of a multiple path band saw slide arrangementwhere the individual slide surfaces are independently adjustablerelative to a common drive pulley and to each other to vary the size ofthe cut lumber pieces.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings wherein like numerals designate correspondingparts throughout the several views, there is shown schematically in FIG.1, a band saw generally designated at 10 which includes an upper locatedguide surface member 12, a vertical support arm 18 extending from a base20 which houses a motor 21 shown in broken lines which drives a drivewheel 14 which is rotatably mounted on an axle carried by the base 20. Aconventional band saw 16 which is in the form of a continuous loopextends over of the curved surface of the surface member 12 and aroundthe drive wheel 14 in a closed path. To effect cutting, a piece oftimber such as shown in broken lines at 29 will be fed against thecutting edge of the band saw 16 on a conveyor (not shown) typically onone side of the drive wheel 14 and guide surface 12.

As shown in the enlarged sectional view of FIG. 2, the guide surface 12is provided with a guide track 22 and, on one side of the track 22 thereis provided a guide shoulder 25 to insure retention of the band saw 16on the guide surface 22 and in a stable position relative to a pluralityof lubricating openings or grooves formed in the surface 22. A number oftechniques are available for reducing friction and assuring smoothoperation and passage of the band saw over the smoothly arcuate surface22. For example, in one form, the track surface 22 may be provided witha plurality of grooves 23 spaced apart along the width of the tracksurface 22 and extending along at least a portion of the path of travelof the band saw 16. A lubricant may be fed under pressure through one ormore tubes 24 to continuously lubricate the underside of the band saw16. Alternatively, the lubricant, such as a hydraulic fluid, may bemixed with air under pressure and pumped to the groove chambers 23underlying the groove openings on the track surface 22.

An alternative structure is illustrated in the top plan view of FIG. 3,where in place of the elongated grooves, multiple rows of openings 26may be provided to extend across the width of the guide member 12.Similar to the embodiment of FIG. 2, each of these openings 26 will beprovided with access to a hydraulic fluid under pressure such as throughtubes 24 which will be connected to a pump 31, FIG. 2, which may alsosupply pressurized air with the hydraulic fluid to the openings 26 tofacilitate the transport of the band saw 16 over the surface 22′. Theamount of pressure used for the fluid whether hydraulic, air or acombination of these, will, of course, depend on the weight of thebandsaw and the tension under which it is operating as will be apparentto those skilled in this technology.

With reference to a FIGS. 4 and 5, there are shown alternative forms ofthe present invention where the guide surface 12A is formed with a base40 and a plurality of tracks 34 each of different radius relative to acenter 33 and each will carry a separate band saw loop. Each track isseparated from an adjacent track by a wall member, one of which isindicated at 52. As will be apparent from FIG. 5, a large number oftracks such as at 42-50 may be provided with decreasing radii from 42 to50. This will have the effect of spatially separating the band saws atthe wood cutting site. The corresponding drive wheel need simply havethe adequate axial width to accommodate the number of band saws used.Also, each of the tracks 42-50 will be provided with either the groovesor openings in its surface described above in conjunction with FIG. 1-3to receive the pressurized hydraulic fluid and/or air but these featuressome of which are indicated at 51 but are omitted from the other tracksfor the sake of clarity. The guide surface in these embodiments ispreferably made from case hardened steel and must be fixed rigidly onthe post 18 to minimize or eliminate vibration during operation of theapparatus.

Referring to FIG. 6 and there is shown a segment of a band saw 60 havingthe usual cutting teeth 62 along one edge and on the opposite edge thereare provided sprocket holes 64 for cooperating with sprocket teeth 66formed on the surface of a drive wheel 14 B. With this arrangement inplace, variations in tension in the band saws moving over the guidesurfaces 12 and 12A will be minimized.

In FIG. 7, a further arrangement is shown where each band saw, 70-80 isprovided with a separate support slide 82-100. The slides 82-100 aresubstantially identical apart from the size of the mounting bases suchas at 102 so that the following description will be understood to applyto each slide 82-100.

Slide 82 has an elongated arm 104 which has an upper slide surface 106which is provided with a plurality of openings such as indicated at 108.The openings 108 are spaced across the surface 106 to underlie the bandsaw 112. The base member 102 is provided with a lubricant feed passage110 which is supplied with a lubricant which may be mixed with air underpressure from a pump (not shown). The band saw 112 has its cutting edgeextending beyond the end of arm 104 as shown.

A mechanism for spacing the slides 82-100 may include a set of drivescrews such as indicated at 118 each of which is connected to a gearsystem 111 rotatably carried in each base member 102 to permit selectiverotation of the gears and activation of corresponding drive screws tochange the spacing between the arm 82-100. Separate electric motors (notshown) may be used to control selected ones of the gears of the systemto effect independent movement of the slides toward or away from eachother. This can be accomplished by control circuitry of a conventionaltype to allow selective actuation of selected gears 113 of the system.

Having described the invention, it will be apparent to those skilled inthis art that various modifications may be made therein withoutdeparting from the spirit and scope of this invention as defined in theaccompanying claims.

1. An apparatus for moving a band saw having an endless, flexible loophaving opposite side edges and a smooth body between said edges, atleast one of said edges having cutting teeth thereon, said apparatusincluding a base supporting a drive wheel mounted on an axle at onelocation and a curved guide surface positioned at a distance from saidaxle, said endless loop extending around a portion of said drive wheeland said curved guide surface so as to define a closed path of travelfor said endless loop with a part of said path including a rectilinearsection to allow access by a workpiece to said cutting teeth toaccomplish cutting on said workpiece, said curved guide surface havingfriction reducing means to facilitate movement of said endless loop oversaid curved guide surface when said drive wheel is actuated to move saidendless loop along said closed path.
 2. The apparatus as claimed inclaim 1 wherein said body of said endless loop includes a plurality ofopenings adjacent on of said edges and extending along said endless loopand said drive wheel including sprocket lugs for engaging some of saidopenings of said endless loop to effect movement of said endless loopwhen said drive wheel is rotated.
 3. The apparatus as claimed in claim 1wherein said guide surface Is provided with at least one grooveextending along said surface substantially in the direction of travel ofsaid endless loop, said groove having a lubricant feed opening forreceiving a fluid lubricant under sufficient pressure to fill saidgroove with lubricant at least during operation of said apparatus. 4.The apparatus as claimed in claim 3 wherein said guide surface isprovided with a plurality of said grooves with each said groove having asaid lubricant feed opening.
 5. The apparatus as claimed in claim 3wherein said apparatus includes a lubricant supply source and a pump tomove lubricant carried by said supply source to said openings in saidgrooves.
 6. The apparatus as claimed in claim 1 wherein said guidesurface is formed from one of a metal, a metal alloy, a syntheticplastic material.
 7. The apparatus as claimed in claim 1 wherein saidendless loop is a metallic band.
 8. The apparatus as claimed in claim 1further including a motor for rotating said drive wheel.
 9. Theapparatus as claimed in claim 2 further including a motor for rotatingsaid drive wheel.
 10. The apparatus as claimed in claim 1 wherein aplurality of endless, flexible loops are provided and said curved guidesurface includes a conforming number of curved guide platforms each ofdifferent radial dimension measured from a common center on said base,each platform having at least one curved side wall to maintain a saidendless loop on said respective platform during operation.
 11. Theapparatus as claimed in claim 9 wherein each said curved platform has acurved face and at least one groove formed in said respective face andan opening for receiving a lubricant under pressure supplied from asource.
 12. The apparatus as claimed in claim 10 wherein said drivewheel has a plurality of tracks conforming to the number of said endlessloops with a said loop riding in a said track on said drive wheel.